How to compare the flex of shafts from different manufacturers

I would like to buy a hybrid club that will fill the gap between my 3-iron and driver.  For my irons I was fitted with a set of Mizunos with the Dynamic Gold X100 steel shafts.  I hit those irons well and I like the feel of the shafts.  For my driver I have a Titleist 913D2 with the Diamana D+ 72 White shaft.  This shaft is maybe a little more stiff than I would like (got it as a gift) but probably the right shaft for me because I tried the Blue shaft in Golfsmith and was less consistent with it.

I'm looking at the Ping G25 and G30 hybrids and will probably go with the 17 degrees.  My swing speed is right around 100mph which on their web site is right in between the s and x-flex.  The X100 and Diamana D+ 72 are considered x-flex, correct?  I'd like to get a shaft that has a similar flex as my existing clubs.  Is there a way to compare the flex across different manufacturers?

I do it in a very non scientific way but it's better than nothing and it works for me.

I hold the shaft in my hands horizontally at eye level, left hand touching the hosel and right hand touching the grip, thumbs under the shaft. I then try to flex the shaft and observe how stiff it feels and how much it bows. I then compare one shaft to another until I find  one I like. The trick is to always hold it the same way and apply the same pressure so you can get somewhat consistent results.

Even "identical" shafts of the same brand can show noticeable differences due to manufacturing tolerances.

Frequency Coefficient Matching (FCM) can be used for comparing shaft stiffness across different models and manufacturers.

The GolfWRX site featured an FCM chart for steel shafts for irons. We have posted it here on TST. The FCM was developed by Royal Precision.

The FCM system uses the cycles per minutes (CPM) as its base. To do test, the shaft butt is anchored in an electronic device which measures the oscillations per minute of the shaft when it is flexed and released. A shaft with 250 cpm was converted into a two-digit decimal number, and given the designation of 5.0 by Royal Precision it its original Rifle shafts. RP considered this Regular flex.

Here's the FCM chart (about 3 years old now).

Things got confusing when RP produced the original Project X shafts. The PX 5.0 flex actually had an FCM of 5.5 - as I found out when the PX 5.0 shafts in my X20 Tours felt harsh on days I wasn't swinging well.

Anyway, that's what was used on steel shafts the past few years.

For graphite and non-steel shafts, more complex codes have emerged that describe the overall shaft profile - going beyond stiffness. Some examples:

• 3 part: Matrix Ozik 6Q3 shaft (stock in Cleveland 588 driver)
• Miyazaka (C.Kua and Kusala models) has 4-digit flex code

Also, there's the Maltby Playability Factor (MPF) 4-unit code, which gauges: stiffness, control-distance balance, hook-or-draw corrections, and launch profile, MPF ratings appear on both steel and graphite shafts which GolfWorks distributes. http://www.ralphmaltby.com/265